Field of the Invention
The invention relates to semiconductor devices and more particularly to a structure and a method of fabricating a Radio Frequency Laterally Diffused Metal-Oxide Semiconductor (RF LDMOS) device.
Description of the Related Art
The widespread use of personal communication products, such as cell phones and wireless LANs, has created a demand for semiconductor devices which can provide certain operational characteristics specific to these devices. Radio Frequency (RF) power transistors are used in communication applications as amplifiers in output stages of transmitters in cellular radios.
Laterally Diffused Metal-Oxide Semiconductor (LDMOS) devices are widely used in silicon field-effect transistors (FETs) for RF and microwave power amplifiers for communication applications. Semiconductor devices that are used in applications such as cellular infrastructure are required to operate at high frequencies. RF LDMOS devices are attractive because they provide good performance at frequencies in a range from 700 MHz to about 3.8 GHz.
LDMOS devices have a drift region between a source region and a drain region. The drift region has a high resistance due to a light doping concentration therein. Therefore, the drift region improves breakdown voltages of the LDMOS devices. However, the conventional drift region cannot enhance cutoff frequencies (fT) of RF LDMOS devices.